United States government agencies have long conducted warrantless secret surveillance, collecting and searching through electronic data for intelligence purposes. However, a newly declassified opinion by the US Foreign Intelligence Surveillance Court (FISC) bolsters concerns about the ways in which law enforcement agencies – such as the Federal Bureau of Investigation (FBI) – may also be sifting through information obtained without warrants.

These searches could have serious consequences for people charged with a crime in US courts.

The FISC opinion is one of several from 2015 that the US intelligence agencies declassified on Tuesday. The opinion deals with Section 702 of the Foreign Intelligence Surveillance Act (FISA), which empowers the agencies to conduct surveillance on US soil with the stated goal of “targeting” someone outside the US who is not a US citizen or permanent resident (that is, someone who is not a “US person”). Although the government characterizes Section 702 surveillance as “targeted,” we know it has used Section 702 for at least two large-scale, warrantless surveillance programs that capture both the content of communications and related data, such as the date, sender, and recipient of a message.

Ostensibly, the government does not “target” US persons under Section 702, which is designed for the collection of foreign intelligence. However, the opinion acknowledges that in practice, the authorities warrantlessly acquire “substantial quantities of information concerning United States persons” under this provision. Also, in a frank revelation, the opinion quotes guidelines confirming that the Federal Bureau of Investigation then conducts warrantless searches (or “queries”) of this secretly collected data in a manner that is “routine and encouraged.” 

Moreover, while a top intelligence official has previously stated that the government will only “use” Section 702 surveillance data as evidence in limited types of criminal cases involving serious offenses, the materials the court quotes suggest that the FBI may be conducting warrantless searches of this data for a much broader range of reasons – including when investigating any federal crime. 

The latter point is especially concerning in light of fears that the government has been using practices such as “parallel construction,” which involves creating an alternative explanation for how the authorities discovered a certain fact (and thereby hiding the true origins of warrantless evidence from defendants and judges). Such practices not only prevent courts from assessing whether the evidence is complete and reliable, but also deprive defendants of the chance to demand any related data that might indicate their innocence.

An independent expert the FISC appointed to comment on these issues raised alarms about the scope and consequences of the FBI’s querying powers, but the court rejected her arguments and unfortunately did not rein in any of these practices.

The opinion casts light on other troubling behaviors by the intelligence agencies, including possible infringements of the attorney-client privilege and failures to keep the FISC fully informed about certain activities. Overall, it highlights how easily secret surveillance powers can be abused and reinforces the urgent need for legal reforms to keep them in check.